class Solution {
public:
    vector<int> searchRange(vector<int>& nums, int target) {
        //二分查找
        if(nums.size() == 0) return {-1,-1};
        int left = 0;
        int right = nums.size()-1;
        int begin = 0;
        //1:找最左区间的target值
        while(left < right){
            int mid = left + (right - left )/2;
            if(nums[mid] < target) left = mid+1;
            else right = mid;
        }
        //2:判断是否有结果
        if(nums[left] != target)return {-1,-1};
        else begin = left;
        

        //3:找最右区间的target值
        left = 0;right = nums.size()-1;
        while(left < right){
            int mid = left + (right - left +1)/2;
            if(nums[mid] <= target) left = mid;
            else right = mid - 1;
        }

        return {begin , left};
    }
};
